1. Field of the Invention
The present invention relates to a method by which a central control unit of an ATM exchange or the like collects large amounts of data from other units, for example, when the central control unit collects billing information, path monitoring (PM) information, and other data from a plurality of distribution/concentration units for each of a large number of setup paths.
2. Description of the Related Art
An ATM (Asynchionous Transfer Mode) exchange includes a plurality of concentration/distribution units, each connected to a plurality of line interface units, for performing cell multiplexing and demultiplexing, and an ATM switch, connected to the plurality of concentration/distribution units, for performing cell switching. The ATM switch is connected to a central control unit (CC) which performs path setup/release control via a DMA (Direct Memory Access) line. The CC collects data such as billing information, the number of passed cells, the number of discarded cells, etc. for each setup path from the distribution/concentration units (hereinafter called the common parts) via the same DMA line. The CC also collects performance monitoring (PM) data, obtained at each line interface unit (hereinafter called the individual part), from its associated common part by DMA communication.
In the prior art, the CC issues an independent command to each individual part, and in response to that, each individual part returns a response status independently of the others. Furthermore, within each individual part, there are a plurality of points or items to be monitored; when the CC makes a data collection request to the individual part, the CC issues a different command for each of such points or items and receives a response status for each of the points or items.
Therefore, the amount of command/status data transferred between the CC and the common parts, and hence the amount of communication between them, becomes enormous, and congestion may result. Since this can cause a detrimental effect on other control functions (such as path control) that require realtime processing, some form of control must be implemented.
To address this problem, the prior art employs a method in which commands associated with data collection functions are given lower priority than other control functions (such as path control), but this method is not intended to reduce the absolute amount of the data transferred in connection with data collection functions. The reality is that no study has been made in the prior art on methods for substantially reducing the amount of communication.